Advanced technologies to adjust the direction of headlamp illumination in accordance with steering angle and vehicle speed, generally called “adaptive front lighting system (AFS)”, have been developed and put into practical use in recent years. One example of such technologies is disclosed in Japanese Patent Laid-Open Publication (JP-A) No. 01-111546.
As shown in FIG. 6 hereof, the disclosed technology varies the length, width and direction of the headlamp illumination according to the angle of the steering wheel and the vehicle speed. Reference numeral 2 denotes a headlamp illumination pattern provided when the steering wheel is turned to the left. Similarly, when the steering wheel is turned to the right, a headlamp illumination pattern denoted by 4 is obtained. The headlamp illumination pattern can thus be redirected depending on the steering angle. A long slim headlamp illumination pattern denoted by 5 is provided when the vehicle is traveling straight ahead at high speeds, while a relatively wide but shorter headlamp illumination pattern denoted by 3 is provided when the vehicle is traveling straight ahead at low speeds. Headlamps of the vehicle are denoted by reference numeral 6.
Operation of the adaptive front lighting system is checked or inspected by the automobile manufacturer before shipment of the vehicle. For such inspection, the automobile manufacturer must prepare a test course or circuit sufficiently large enough to permit actual traveling of the vehicles. When darkness arrives or during nighttime, finished vehicles are put into actual run or traveling on the circuit so as to determine whether the adaptive front lightening system operates in a specified manner depending on steering angle and vehicle speed. Obviously, those vehicles produced during daytime must stand by in an appropriate space, such as a parking lot, before the inspection during darkness is started.
The conventional operation checking method discussed above requires a large amount of facility cost due to the necessity of the relatively large test circuit and parking lot.
Furthermore, due to a large time lag existing between the production and the checking of the vehicles equipped with the adaptive front lighting system, even if a fault is detected by the checking process, information about the detected fault is fed back with a great delay to a relevant part of an automobile production and assembly line. This allows production of a large number of vehicles with defective adaptive front lighting systems installed therein.
It is, therefore, an object of the present invention to provide a method of checking operation of an adaptive front lighting system, which can be applied to on-line inspections of an automobile production and assembly line.